I started using remote logging, non-BSD style, from ROS 5.5 to a Linux server running syslog-ng.
In principal, it works, however, I am missing the identification/source/hostname/Identity of the log messages.

For instance, I see on my LINUX in /var/log/messages:
Jul 12 14:07:08 reinerotto system,info,account user admin logged out via local

Frankly speaking, I have no idea, where "reinerotto" originates from, but I would expect some type of host identification here, like the "Identity" from the MT-box..

Any idea ?

it seems you routers ip address in logging linux host hosts file

No.

I did manual "Reverse DNS" for the IP of the MT-box, and found out, that "reinerotto" is the user name, the MT-Box uses to log in to the ISP.

Situation improoved, now I have the IP at least:

Jul 12 16:32:40 xxx.yyy.zzz.123 system,info,account user admin logged out

The trick is in syslog-ng.conf:
options { keep_hostname(yes); long_hostnames(off); use_dns(no); .....

However, it might be a good idea, to include the "Identity" of the MT-box in the (remote) log-message.